Ernie Sims is a former first-round draft pick. This week, maybe he’ll be that guy.

“I want to be that guy,” he said. “Interceptions. Tackles for loss. Eighty-something tackles right now. On the way to the Pro Bowl.

“I want to be that guy.”

The Dallas Cowboys are not asking for that much from Sims, a nine-year veteran signed off the street last year. But they need him to be a steady, stable performer at middle linebacker in the two or more games Sean Lee is expected to miss because of a hamstring injury.

Sims will be the most experienced member of a reshaped linebacker corps that the Cowboys will take into Sunday’s game against the New York Giants. Third-year pro Bruce Carter will play full time at the weakside spot for the first time since Week 3. Rookie sixth-round pick DeVonte Holloman will play the strongside spot because veteran backup Justin Durant is also injured.

Behind them are only undrafted rookie Cameron Lawrence and special teams veteran Kyle Bosworth.

“I think it’s a big moment,” Sims said of his chance to start. “A real big moment. A lot of eyes are on me to see how I’m going to approach the situation. I know one thing, I’m not afraid. I’m stepping up to the plate. I’m studying. I’m meeting with Sean, meeting with anybody who’s willing to give me the extra advice, extra coaching.”

Sims was a full-time starter his first three years in the league, after the Detroit Lions took him with the ninth overall pick in 2005, but he did not earn a second contract there. In 2010, he started 15 games for the Philadelphia Eagles but was not brought back. He played in 13 games for Indianapolis in 2011 and again didn’t stick.

In October last year, he came to Dallas after Lee was lost for the season to a broken toe. The Cowboys did choose to bring him back, and now, he is getting his best chance since Detroit to make a lasting impression.

“That I can play in this league,” Sims said, asked what he wants to show. “I’m a starter in this league. I’ve been doing it for a long time. I can make plays in this league. I think that’s what I want to prove.”

Sims said he has played only “average” this year in a rotation with Carter on the weak side, but the Cowboys have long been impressed with his intensity and desire to hit.

“One word: physical,” defensive tackle Jason Hatcher said, asked to describe what Sims brings to the table. “He is trying to hit everything that moves. I love Ernie to death. He’s going to blossom. I’m excited to see it. He’s ready for it. He’s been waiting on this opportunity and now it’s here. I’m just going to sit back and enjoy the show because he’s going to ball out.”

Coach Jason Garrett said the tempo Sims sets in practice is one of the intangibles he possesses.

“He loves ball. He’s competitive,” Garrett said. “He practices as hard as anybody on our football team. He’s one of those guys, in a very good way, you’re always saying, ‘Ernie, it’s shells today.’ You know? ‘It’s not full pads. It’s not tackle.’ You’re always pulling him away from players. It’s just the way he plays.

“Some of the best players I’ve ever been around have that same kind of mentality.”

Sims is not the only linebacker who will have a chance to prove himself.

Carter, benched in the San Diego game this year, will aim to reproduce the high level of performance he showed last year following Lee’s injury.

“For a guy like me, I’ve just got to go out there and play my game, just remain calm,” Carter said. “You don’t want to go out there and try to put too much pressure on yourself and then you’re out of whack completely. You’ve just got to go out there, play your game, help out, communicate, make sure everybody’s on the same page and go from there.”

And Holloman will try to show not only that he is healthy after missing five weeks with a spinal contusion, but also that his intriguing preseason — which included two interceptions — carries over into the regular season.

“He’s an inexperienced player. He hasn’t played that much for us,” Garrett said. “But when he’s played, he’s done some good things, you know, as a special teams guy, spot play on defense. Has a good instinct for playing. Seems to be around the ball and makes a lot of plays.”

But it begins with Sims. His performance will come under scrutiny most because he is replacing the defense’s leader and one of its most productive players.

“I’ll never be perfect,” Sims said. “But you can bet your last dollar, by the end of this week, come Sunday, I’m going to be pretty good.”